The spectacular bloom of a magnolia may be a very common sight in gardens but in the wild, it is a different story.

A new report has found that over half the world's magnolia species are facing extinction in their forest habitats.

The Red List of the Magnoliaceae is published jointly by Botanic Gardens Conservation International (BGCI) and Fauna and Flora International (FFI).

Threats to their existence include the destruction of habitat to make way for agriculture, and over-exploitation.

"There is a strong chance that these species will become extinct unless we take action now," said Sara Oldfield from BGCI.

"That would be a tragedy because they're so important in local livelihoods and also we would be losing some beautiful trees for ever," she told BBC News.

The Red List identifies 131 wild magnolias as being in danger of extinction, from a global total of 245 species.

Survey work is a critical to the conservation effort

Magnolias are among the most ancient groups of flowering plants and have long been cultivated by mankind.

Some specimens growing in the precincts of Chinese temples are estimated to be up to 800 years old.

"Apart from garden plants, magnolias are used as food sources and for medicinal purposes," explained Jim Gardiner, curator at the Royal Horticultural Society's garden at Wisley, Surrey.

"They're also used as timber products. They have a whole variety of uses because magnolias produce a very durable, light-coloured wood."

The BGCI and FFI say the significance of the plants' decline lies not only in the threat to the genetic diversity of the family, but also because magnolias are a highly sensitive indicator of the well-being of the forests in which they are found.

Some two-thirds of known magnolia species are found in Asia

Some two-thirds of known magnolia species are found in Asia, with over 40% occurring in southern China.

According to the report, half of all wild Chinese magnolias are at risk of extinction.

In the Americas, north and south, where magnolias are also found in the wild, a similar picture is emerging.

In Colombia, for example, the report concludes that the threat of extinction hangs over 30 of its native species.

Later this month, at the 3rd Global Botanic Gardens Congress in Wuhan, China, a survey will be launched to document those threatened magnolias species held in collections around the world.

This will enable BGCI to identify precisely which threatened species still need to be brought into botanic gardens and arboreta to secure their genetic future, and underpin current conservation efforts in the wild.

"We are aiming to restore wild populations of key magnolia species in Yunnan Province," said Dr Georgina Magin at the Global Trees Campaign, a BGCI/FFI initiative.

"We hope to be able to extend this work to take action for other species, both in China and in other parts of the world."